A belt-type conveyor is known from commonly owned U.S. patent applications Nos. 385,065, 388,592, and 461,534 respectively filed June 4, 1982, June 15, 1982, and Jan. 27, 1983 which is used for transporting bulk material mainly underground along a closed path traversing at least one loading or unloading zone. Such a conveyor system has a track on the path and including a main rail following the path outside the zone and having ends at the zone, respective intersections at the zone connected between the rail ends and respective right and left rail branches extending between the intersections. An endless conveyor belt extends along the path and through the zone and has right and left longitudinal edges provided with respective endless rows of longitudinally spaced right and left trucks alternating with one another along the path and each having a lower end attached to the respective belt edge and an upper end riding on and displaceable longitudinally in the rail. An endless and flexible tension-transmitting drive element extends along the path and through the zone and is connected at least indirectly to the belt and trucks. A drive is connected to the drive element for advancing the belt and trucks along the path in a transport direction. Relative to the transport direction, at the upstream intersection the right trucks pass into the right branch and the left trucks into the left branch. The belt is closed and tubular outside the zone when its right and left trucks are all in the main rail and is open in the zone when the right trucks are in the right branch and the left trucks are spaced therefrom in the left branch.
Such a conveyor can move bulk material in a mine relatively neatly, normally along underneath the mine roof. The bulk material is well contained as it is transported in the belt when its edges are pulled together to make the belt tubular and can be loaded into the belt and unloaded from it relatively easily when the belt edges are pulled apart, making the belt flat.
This type of system, nonetheless, is invariably wholly independent of any type of conveyor or transporter for other then bulk material. Thus people, tools, and equipment must be moved about by a wholly different transport system, typically by means of automotive tractors. These tractors are expensive both as regards first costs and operation expenses, and therefore are not provided in sufficient quantities to make then convenient.